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Discussion Starter · #1 ·
97 4 banger Check Engine light's on & Heep is running VERY bad...

After Diag. dealer sez TDC sensor needs replacing... Any ideas where this sensor is? They said $255 total for replacement.

Is it like a MAP sensor that's easy to get to for replacement on my own? or is it a PITA & worth paying them to do it?

I told 'em I'd call back in 30 minutes.
 

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Sounds like they are talking about the Crank sensor, on the 4.0 it is on the top off the bellhousing at about the 11 o'clock position, its not hard to change on the 4.0, two bolts and one wire.

I am thinking TDC is the Top Dead Center Sensor, or Crank Sensor, but I have been wrong!

Buy the part, I bet you can do it yourself, but confirm thats the sensor they are talking about.
 

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Discussion Starter · #5 ·
Yep. Top Dead Center sensor... that's what they said.

Trouble is, when it goes... the Jeep :skull: dies :skull:

AND... it's raining here & I got no garage. :mad:
 

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TPIJeep said:
If you want to shell out the coin so be it, but on the 4.0 is takes about 5 min to change.
if indeed TDC sensor = crank position sensor (sounds like it)

just run down to your nearest gasstation or carwash and change it out real quick under their awning. Like has been said, 11 o clock position on the bellhousing(when sitting in the drivers seat, drivers side), 5-10 minute job. ;)
 

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Discussion Starter · #8 ·
ha ha...
i just talked to 'em... they said they'd fix the sensor, but it's got blow-by. and they'd decline any other work "because of modifications that have been made."

mods= air intake and electric fan.

what a bunch of dumbasses.

I'll go buy a friggin' sensor & swap it out.

THANKS!!
 

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Kilby - when you said running very bad you weren't by any chance meaning that the engine was running really rough under load and stumbling were you?
 

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Discussion Starter · #10 ·
McJeep said:
Kilby - when you said running very bad you weren't by any chance meaning that the engine was running really rough under load and stumbling were you?
Yes, actually... that is what I mean.

What is it, doc?
 

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I got my last CPS for about 65$ (OEM mopar part) and it takes about 10 min to install just undo the two bolts on the bellhousing and bolt the new one up - just be sure to route the wire away from anything hot...

If yours won't start try unplugging and replugging it a couple of times - usually enough to get the motor to fire up...

HTH

Matt
 

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Discussion Starter · #12 ·
It starts okay... just doesn't run too good.

Dealer said $125 for the sensor...
Car Quest said $160...
Napa said unavailable.

:mad: :mad: AND.... WHAT THE HELL IS BLOW BY??? I had that in my old XJ & it just puked oil outta everywhere. What can I do about that? MOTOR SWAP??
 

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put some 80/90w in there, that should hold :p


:flipoff2:

Kilby said:
It starts okay... just doesn't run too good.

Dealer said $125 for the sensor...
Car Quest said $160...
Napa said unavailable.

:mad: :mad: AND.... WHAT THE HELL IS BLOW BY??? I had that in my old XJ & it just puked oil outta everywhere. What can I do about that? MOTOR SWAP??
 

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Kilby said:

:mad: :mad: AND.... WHAT THE HELL IS BLOW BY???
Blow by is when combustion gasses are getting past the rings and that tends to pressurize the crankcase, which tends to blow oil out the pvc valve. Its not a good sign! I would run a compression check on it so see if its one cylinder or all the cylinders!
 

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I had to get out the phone book and start calling around - the prices ranged from 40$ to ~150$ - temper that with who has it on the shelf and pick your poison...

Blowby is just what motor does when the tollerances open up a hair past what they should - unless your smoking out the back or eating lots of oil I wouldn't loose much sleep over it - you may have to change the oil and air filter more often - just get a K&N and clean the bugger every once and a while...

Stealerships just love the scare tactics - works great for soccer moms :flipoff2:

I love the look on the tech's faces when I pull up for some obtusely shaped OEM only bolt I need and I have a cracked header or no muffler, ect - The exo cage kinda throws them; they don't know where to start!

I must break the really odd stuff as 90% of the time I get the "that part is no-longer produced and not avaliable seperately; we have none on the shelf..." :rolleyes:

Good luck

Matt
 

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Kilby said:
What is it, doc?
Bwaaahahahaha, I dunno but it's the same thing I've been trying to diagnose for a couple weeks now!:D

'Picking up a CPS on the way home tonight I guess ;)

Rob
 

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Actually Brad (This is Brad Kilby right? sorry if I fawked up) I was just talking to one of my favourite parts guys (usually pretty right on with advice) and he mentioned that the new epoxy coils can have a tendency to gradually degrade and fail under load the way we have been experiencing. Think I'm gonna swap a new coil in instead. $40 cdn versu $87 cdn. I'm gonna eat that cost as tuneup as the coil that's in there now has been there for 7 years.

Oh, and he also mentioned that he's never seen a cps degrade gradually, it's always been go or no go.

Keep me posted on your cps and I'll let ya know how I make out.

Rob
 

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here is a quick trick i found to test the cps. i believe it works if the jeep will turn over but not start. the trick is to unplug the sensor for a short period of time then plug it back in. If the jeep runs then it is the sensor. also have you run the codes yet to see what they say
 

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Kilby, how'd ya make out?

Well I guess you can teach an old dog new shtuff. Swapped in a new coil today and poof...it's running better than it has in quite a while. I have always been under the impression that coils either did or did not work but apparently that was just the older ones. (sure, now I'm dating myself) Apparently the new ones can and will degrade with time and vibration etc (hmmmm, wheeling wouldn't stress them then would it? ;0).

Anyway, if you haven't already put in a new cps Kilby, it might be worth borrowing a buddy's coil to do a test.

Hope your day goes as well as mine is now that things are back to smooth running. :D
 
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